Rope feed piston assembly

ABSTRACT

A FEED CABLE PISTON ASSEMBLY AND MORE PARTICULARLY MEANS FOR KEEPING THE FEED CABLE RELATIVELY FREED FROM DIRT BUILD-UP AND MEAND FOR SECURING THE CABLE TO DRIVING PISTON HEAD.

J. E. GORDON 2 Sheets-Sheet 1 INVENTOI? JOHN E. GORDON Feb. 20, 1973ROPE FEED PISTON ASSEMBLY Filed June 2, 1970 Feb. 20, 1973 J. E. GORDON3,717,071

ROPE FEED PISTON ASSEMBLY Filed June 2, 1970 2 Sheeps-Sheet 2 IN VE N TOF JOHN E. GORDON United States Patent 3,717,071 ROPE FEED PISTONASSEMBLY John Edward Gordon, 337 Main St. E., Gait, Ontario, CanadaFiled June 2, 1970, Ser. No. 42,789 Int. Cl. F01b 9/00 US. Cl. 92-137 4Claims ABSTRACT OF THE DISCLOSURE A feed cable piston assembly and moreparticularly means for keeping the feed cable relatively free from dirtbuild-up and means for securing the feed cable to a driving piston head.

With some feed cable apparatus presently in use, a feed cable pistonassembly is used to provide power for the feed cable apparatus. Withsuch prior feed cable piston assemblies, the feed cable is generallyterminated at the piston and fastened thereto. Experience has shown thatsuch previous meas of fastening the end of the feed cable to the pistonis unsatisfactory in that premature wear and breakage develops at theconnection and because such connection is located within a relativelysealed piston chamber, such wear is diflic-ult to observe and thebreakage is difiicult to repair without disassembly of the pisnotassembly.

By use of the present invention which includes a compression assemblyfor securing the feed cable to the pis ton, the cable is passed throughthe piston unbroken and accordingly occurrences of feed cable breakageand/or wear within the piston assembly is reduced.

Another feature of the present invention is passing the feed cablethrough sleeves made of urethane or the like. Such sleeves are securedat each end of the piston assembly and permit a controlled outward airleakage because of the uneven outer surface of the cable therebypreventing dirt from being carried by the feed cable to the interior ofthe piston assembly. The sleeves additionally provide a relativelyfrictionless wiping of the feed cable as it passes therethrough. I

These and other objects and advantages of this invention will becomemore readily apparent from a reading of the following description anddrawings, in which:

FIG. 1 is a side cross-sectional view of a feed cable piston assemblyconstructed in accordance with the principles of this invention;

FIG. 2 is an expanded side view, partly in section, of the piston headshown in FIG. 1 and the means for securing such piston head to a feedcable passing therethrough; and

FIG. 3 is a side-elevational view of a drilling device embodying theprinciples of this invention and with a portion of the mobile sidesupports and frames being omitted.

An elongated feed cable piston assembly 50 comprises: an elongatedhollow cylindrical piston casing 52; casing end caps 54 which sealinglyreceive respective ends of casing 52 within the inner ends thereof; and,as shown, a double acting piston head 56 which is slidingly andsealingly received within casing 52 thereby separating casing 52 into aretracting chamber portion 58 intermediate the rearward ends of head 56and casing 52 and a feeding chamber portion 60 intermediate the forwardends of head 56 and casing 52.

A suitable elongated load transmitting flexible member such as feedcable 51 has a continuous unbroken portion thereof extendinglongitudinally through assembly 50 and fixedly secured to piston head56in a manner as hereinafter described. For purposes of the hereinbeforeand hereinafter description of piston assembly 50, forward and rearwardshall refer respectively to the left and right as viewed in FIGS. 1 and2.

End caps 54 have a generally cylindrical cross section and include aninner portion 62 and a smaller diameter outer portion 64. Inner portion62 has a bore '65 therein to receive the respective end of casing 52therein as specified above and is provided with a fluid conductingconnection 63 communicating between the interior of each end cap 54 anda source of pressure fluid (not shown) such as compressed air. Outerportion 64 has a three-stepped bore 66 extending axially therethrough.Bore 66 includes bore portions 68, 70 and 72 which respectively progressinwardly from the outer ends of portion 64 and have respectivedecreasing diameters.

A cylindrical elastomeric sleeve 74 having an axial length and outerdiameter thereof substantially equal to the respective axial length anddiameter of bore portion 70 is received within bore portion '70. An endcap plug 76 which has a central bore 78 therethrough is releasablyreceived within bore portion 68 to retain sleeve '74 within bore portion70. Bore 78, bore portion 72 and the inner bore of sleeve 74 are inaxial alignment and have diameters thereof substantially equal to theoutermost diameter of the feed cable 51 thereby permitting cable 51 topass therethrough during the reciprocal operation of piston assembly 50.

Pressure fluid leakage around the outside diameter of sleeve '74 isprevented by sleeve 74 seating against the inner end of plug 76 when therespective feeding or retracting chamber is pressurized from a suitablefluid pressure source (not shown). Leakage of pressure fluid does takeplace between the sleeve 74 and cable 51 due to the uneven outer surfaceof the cable 51 caused by the strands from which the cable 51 ismanufactured. Such leakage prevents dirt and the like from being carriedinside piston assembly 50.

Inasmuch as sleeve '74 is made of an elastomeric material, the abovedescribed leakage is substantially constant regardless of the pressurewithin the feeding or retracting chamber for when the pressure withinchamber 58 or 60 increases, such increase in pressure tends to compressthe respective sleeve 74 and, as such, causes it to fit more snuglyabout cable 51 and thus reduce leakage at higher pressures. Thiscompression of sleeve additionally compensates for excessive wear ofsleeve 74 by maintaining a snug fit between sleeve 74 and cable 51.

Piston head 56 has a three-stepped bore 80 extending axiallytherethrough for receiving feed cable 51 therein. Bore 80 includes boreportions 82, 84 and 86 which respectively progress forwardly from therearward end of piston head 56 and have respective decreasing diameters.'Feed cable 51 is fixedly engaged with piston head 56 by means of acompression sleeve assembly 81 which is insertable within bore portions82 and 84.

Compression assembly 8-1 includes a cylindrical elastomeric compressionsleeve 88 which has an axial length thereof less than the axial lengthof bore portion 84 and which is received within portion 84 such that theforward end thereof is seated at the forward end of portion 84 and therearward end thereof is intermediate the axial ends of portion 84. Asuitable cylindrical spacer sleeve 90 is insertable axially within bore80 such that the forward end thereof is engageable with the rearward endof sleeve '88 and the rearward end thereof is located intermediate theaxial ends of bore portion 82. Bore portion 82 has the rearward endthereof threaded for threadably receiving a compression screw 92partially therein. Compression screw 92 has a bore 94 extending axiallytherethrough. Bore 94, bore portion 86, the inner bore of sleeve 90 andthe uncompressed inner bore of compression sleeve 88 are in axialalignment and have diameters thereof substantially equal to theoutermost diameter of feed cable 51.

With such an arrangement of the compression sleeve assembly 81 ashereinabove described piston head 56 is fixedly secured to feed cable 51by initially threading cable 51 through the piston head 56, thecompression sleeve 88, the spacer sleeve 90 and the compression screw92. After such initial threading, the piston head 56 is adjusted to thedesired location on the length of cable 51. The compression screw 92 isthen tightened thereby exerting an axial force on compression sleeve 88through spacer sleeve 90 which communicates therebetween. The axialforce compresses sleeve 88 thereby resulting in the elastomeric bodythereof flowing into and around all the crevices formed by the wirestrands of cable 51 and thus obtaining a firm but undamaging grip oncable 51. The compressed sleeve 88 additionally provides a fluid tightseal within bore 80.

It is to be noted that a feed cable assembly 50 as describedhereinbefore is intended for use in any type of apparatus making use ofa feed cable to feed and/or retract an element during the operation ofsuch an apparatus. An example of the use of a feed cable assembly ofthis invention is shown and illustrated in my copending United Statesapplication Ser. No. 43,138, filed June 3, 1970 and assigned to the sameassignee as is this invention.

The above copending application shows and more completely describes theemployment of this invention in a drilling apparatus such as thatdepicted in FIG. 3 which includes a drill guide frame assembly 12supported and rendered movable over a surface by a crawler sup port 14of a type well known in the art. Frame assembly 12 is suitably movablysupported by a .well known boom assembly 1 6. Frame assembly 12 supportsa drill motor 20 thereon, which motor 20 is axially movable with respectto frame assembly 12 by means of the feed cable assembly 50 of thisinvention.

Although preferred embodiments of various features of this inventionhave been described and illustrated herein, one skilled in the art canreadily embody the principles of this invention in other forms to obtainthe same operation and advantages without departing from the scope ofthe invention, for example: although a double acting piston assembly isdescribed hereinabove the invention herein can be adapted for use with asingle acting piston assembly such as by feeding an element by means ofthe feed cable assembly of this invention and retracting by othermechanical means or gravity; the compression sleeve can be positioned inother loca tions than as described; different means of providing anaxial force on the sleeve 88 are contemplated; a compression assemblycan be provided at each end of the piston head if desired; sleeve 88 canbe constructed of partially elastomeric materials and partially of othermaterials; other means for wedging the feed cable to the piston head arecontemplated; and the like.

The description herein does not limit the structure of this inventionand the invention is defined by the scope of the claims set forthhereinafter.

What is claimed is:

1. A feed piston assembly comprising: a substantially cylindricalelongated body element; an axial bore through said body element; anelongated load transmitting member having a continuous portion extendingthrough said bore; a deformable member received within said 'bore andencompassing a portion of said load member; means attached to said bodyelement for compressing said deformable member into frictional andsealing engagement with said portion of said load member and said bodybore; a casing having an elongated intermediate portion with an axiallyextending bore therethrough within which said piston receiprocates; endportions of said casing having bores therethrough axially aligned withsaid bore through said intermediate portion; and said load transmittingmember being a driving cable passing through said aligned bores.

2. A piston assembly as specified in claim 1 wherein said deformablemember is formed at least partially of elastomeric material.

3. A piston assembly as specified in claim 1 additionally includingelastomeric wiping sleeves fixedly disposed about said cable within saidbores through said end portions, said wiping sleeves having an outerdiameter thereof substantially equal to the diameter of respective boresthrough said end portions and having an axially extending boretherethrough of a diameter substantially equal to the outermost diameterof said driving cable to provide for a preselected amount of pressurefluid leakage outwardly between said cable and said casing ends.

4. A piston assembly as specified in claim 1 wherein said means attachedto said body element includes a member having at least a portion thereofthreadably received within said body bore.

References Cited UNITED STATES PATENTS 2,094,124 9/1937 Huffman 173-1471,258,580 3/1918 Lassiter 24-126.3 982,727 1/1911 Jones 24-155 986,8743/1911 Thomlinson 24-155 2,639,692 5/1953 Akers 92137 3,535,985 10/1970Attebo J 92137 MARTIN P. SCHWADRON, Primary Examiner A. M. ZUPCIC,Assistant Examiner US. Cl. X.R. 173147

